Corneal contact lenses are a critical part of vitreoretinal surgery, especially macular surgery. The contact lenses allow a surgeon to visualize the macular as well as other structures of the eye at high magnification. Surgeons typically employ a separate lens that can be placed directly on the eyeball and allow focusing to be extended to the retina and other areas in the back of the eyeball.
In order to be effective, a contact lens must be stably positioned and centered on the cornea of the eye at the site of the surgery. This is difficult to achieve due to the cornea curved contouring. The slipperiness is made worse by the use of viscous coupling agents (such as, for example, viscoelastics or hydroxymethyl cellulose), which are used to avoid bubble formation beneath the contact lens during the surgery.
The lens placed on the eyeball floats on a thin layer of fluid and tends to slide about the surface of the eye. In order to overcome the sliding displacement and to hold the lens in place, a surgeon or a surgeon's assistant constantly monitors the lens position and uses a rod or other extension (handle) to push the lens back to a desired location. In order to perform this task, the surgeon or surgeon's assistant must have a profound experience in vitreoretinal surgery which is not always the case.
For example, U.S. Pat. No. 5,070,290, describes the gonioscopy, which is a technique used for viewing inner portions (such as the retina and the anterior chamber angle) of the eye for evaluation, management, and classification of normal and abnormal structures of the eye. The gonioscopy technique uses devices known as gonioscopes to enhance visibility of the trabecular meshwork and anterior chamber angle during surgical procedures. The gonioscope is hand-held by a surgeon in place over the patient's cornea while he/she performs the surgical procedure.
The gonioscope described in U.S. Pat. No. 8,070,290 includes the Hill gonioprism positioned on a patient's eye. The gonioscopic optical element, which includes one or several lens, such as optical prism(s), is received in a lens retainer, and a handle or a grip is attached to the lens retainer. During the surgical procedure, the gonioscopic optical element is positioned over or on the patient's eye, e.g. the cornea of the eye.
A light source is used during the surgery which emits light toward the patient's eye. The light source may be configured such that light from the source illuminates the patient's eye, the anterior chamber, and the eye structures near the anterior chamber, e.g. trabecular meshwork, such that one or more of these structures reflect(s) light incident from the light source.
The light source and the prism(s) is (are) arranged in such a fashion that the light from the light source is reflected by the patient's eye (or specific optical structures), traverses the gonioscopic prism(s), and is redirected, e.g., refracted and diffracted, by the gonioscopic prisms. An image is formed of at least part of the patient's eye and this image is viewed using a microscope.
The handle of the gonioscope described in '290 patent is used to stabilize and centralize the entire gonioscope structure. This arrangement generally requires assistance of a surgeon assistant to manipulate the handle of the gonioscope during the procedure.
Landers has improved upon the gonioscope prism requiring manual manipulation of the handle during the ophthalmic procedure surgery, and provided a “hand-free” solution for the problem which eliminates the need for a surgeon assistant to manually stabilize and centralize the contact lens.
The Landers' system uses a lens ring which circumferentially envelopes sides of the contact lens, and serves as the lens holder. To stabilize and centralize the contact lens at the desired site during the procedure, the lens ring is secured to the conjunctiva/sclera with a pair of fixation sutures. The contact lens is placed inside the lens ring which remains in place by the fixation sutures, and thus, the contact lens is maintained in place and sutured throughout the duration of the macular surgery.
Fixation sutures, however, are not welcomed by a majority of ophthalmologists, especially glaucoma surgeons, due to traumatic effects of the fixation sutures to the cornea or sclera of the eye. In addition to the traumatic nature of the fixation sutures (which typically cause bleeding which can obscure view of the surgical site), if the sutures are excessively tight, the cornea can be disturbed and the sutures may break during the surgery, which is definitely a disadvantage of the suturing approach. On the other hand, if the sutures are too loose, the displacement of lens may occur, which can undermine the surgery efficiency.
Since the Landers development, various solutions for “suture-less” contact lens stabilization have been developed. For example, as presented in U.S. Pat. No. 5,963,301, the lens is constructed with a flange that is shaped to conform to the general curvature of an average eye. In order to be attached to the eye surface, and thus stabilizing the lens in place, the flange is formed with a number of peripheral openings or recesses sized to accommodate various types of instruments to be inserted into the eye during the surgery. The flange is formed with fittings to which a vacuum is applied in order to pull the flange into contact with the sclera of the eye by creating a vacuum between the flange and eye to enhance holding the lens device in position.
Another method for overcoming the problem of contact lens movement during surgery is disclosed in U.S. Pat. No. 6,120,147 where the lens are replaced with flexible lens having a relatively flexible flange which is fixed in place by capillary action.
U.S. Patent Application Publication No. 2014/0307229 and related U.S. Pat. No. 9,339,184 describe a contact lens for vitreoretinal surgery where a contact lens assembly has a central lens and a circumscribing flange. The lens has an eye contact surface shaped generally to a radius of curvature of a cornea of an eye. The flange comprises a sterile sponge-like liquid absorbent flexible material having a central aperture for fitting snuggly about an outer circumference of the lens and extending radially outward therefrom.
During the procedure, the lens is mated with a flange and the lens/flange assembly is then placed on the wetted eye of a patient. Additional wetting compound, such as sterile saline solution, is then spread onto the flange until the flange is generally situated. The lens can then be moved as necessary for viewing and the wetted flange holds the lens in a desired position.
It has been found that most of the prior art devices slide off of the cornea during the surgery. The surgeon, or the surgeon's assistant, must push the lens back to the center of the cornea a number of times during critical steps of the surgery. This may cause loss of the surgical field at a crucial moment. Thus, the suture-less systems currently available, are not preferred by many surgeons. The surgeons use the sutured lens ring even though it takes additional time and causes superficial bleeding from the conjunctiva.
It is highly desirable to provide a suture-free and hands-free non-sliding corneal contact lens stabilization and anchoring system for vitreoretinal surgery which does not require monitoring and manual positioning of the lens during the surgery and which provides hands-free effective stabilization and centralization of the lens during a surgical procedure in trauma-free manner.
One of the important topics discussed among glaucoma surgical specialists is micro invasive glaucoma surgery, further referred to herein as MIGS. The MIGS refers to a group of relatively recent glaucoma surgery techniques that are gentler and involve less tissue disruption than traditional glaucoma surgeries (such as trabeculectomy and shunts).
The glaucoma specialists indicate that there is a significant learning curve in order to master MIGS technique. Operating directly on the tiny trabecular meshwork is challenging. Obtaining visualization of the angle is the most difficult part of the learning curve and the key to mastering this surgery. The critical angle of the peripheral cornea may cause total internal reflectivity of light. For that reason, special contact lenses are needed to allow visualization of the angle structures.
Even with a surgical gonioprism, the critical angle surgery is difficult to perform. Mastering the usage of the current surgical gonioprism is a significant barrier for many surgeons. In order to visualize the angle structures, a surgeon rotates the patient's head to the side by 30°, to the microscope 30°, and to steady a hand-held surgical gonioprism on the cornea with their non-dominant hand (as shown, for example, in U.S. Pat. No. 8,070,290). This requires a significant amount of practice and steady hands. The surgeon cannot learn the technical steps of the MIG surgery, such as implanting the stent or cutting into the trabecular meshwork, until they can consistently obtain a steady view of the angle.
Glaucoma surgeons are universally opposed to placing fixation sutures. They do not want to cause any trauma to the cornea or sclera of the eye. Simplifying and improving the visualization of the critical angle during the surgery, without causing tissue injury by fixating sutures can remove the barriers that are currently limiting adoption of this newest type of glaucoma surgery, i.e., MIGS.
U.S. Patent Application Publication No. 2012/0099077 to Abt describes an ophthalmic optics (lens) which includes an aspheric anterior surface and a posterior surface having a shape substantially corresponding to the shape of a human cornea. In order to support the lens on the cornea, Abt uses a surrounding flange. Adhesive, weights or fibers (for the lens stabilization) are embedded in the tabs of the flange for registering with the sclera to create stabilization forces by the tabs' interaction with the sclera.
In Abt, the stabilizing structures (which are embedded in the tabs of the flange) do not come in contact with the tissues of the eye at the operation site. They are positioned above the eye tissues at the sclera (and thus are laterally displaced from the operation site) and “float” above the sclera area separated from the sclera tissues through the layer of the tear film and viscous layer. This “floating” on the slippery film does not provide a reliable stabilization of the lens at the operation site in Abt arrangement.
Abt's stabilizing mechanism produces shear forces displaced laterally from the cornea area and applied to the sclera (away from the cornea), and is neither formed integrally with the bottom surface of the lens nor extends vertically downward from the bottom of the lens into contact with the procedure site (such as the cornea).
The only structure in Abt system which does penetrate through the tear film of the eye are trocar cannulas. However, Abt does not consider the trocar cannulas as a mechanism for securing the optical lens to the eye of the patient. Abt emphasizes that the fastening means include packing material and/or mechanical fasteners, which are used to secure the optical lens to the patient's eye to stabilize the optical element on the eye and permit the appropriate insertion of the trocar cannulas. Thus, in Abt, trocar cannulas by themselves do not constitute the anchoring mechanism, and other fastening elements are used which facilitate the insertion of the trocar cannulas.
In Abt, the trocar cannulas are dimensioned in the mm range, and penetrate deep into sclera area. It is understood that such trocar cannulas dimensions are dictated by the operational requirements, however, they create a highly traumatic action on the tissues of the eye.
Another disadvantage of Abt is that the lens “is self-retaining on the eye through capillary attraction”. The stability of the lens in Abt relies on a capillary attraction, which is not desirable since the capillary attraction forces tend to pull blood and air bubbles beneath the contact lens during surgery. This phenomenon can impair the surgeon's visualization during critical moments of surgical procedure.
It would be highly desirable to provide a stand-alone mechanism which is integral with the optics and which creates vertical forces registered with the cornea area for directly stabilizing the contact lens on the cornea where the contact lens can be stabilized and centralized over the surgical area of the eye in a suture free non-sliding manner without the need for manual repositioning and centralization of the contact lens during the operation.
It also would be desirable to provide ophthalmic optics equipped with microstructured anchoring elements which are formed integrally with the bottom of the contact lens or in close proximity to the periphery of the contact lens so that when the contact lens is placed on the cornea, the microstructured anchoring elements pass vertically downward to penetrate through the tear film and viscous layer on the cornea, and come into direct contact with the cornea, i.e., in registration with the operation site to provide a vertical compression force applied to the cornea by the bottoms of the microstructures, which creates an increased friction between the microstructures and the cornea, which prevents lens from sliding from the cornea, thus forming a highly reliable mechanism of anchoring the lens in position during the operation.